Scaffold drive and steering unit

ABSTRACT

Drive and steering attachments for application to and use with scaffold units of the type used in connection with construction and maintenance activities. A reversible drive motor associated with one scaffold support drive and steered wheel propels the scaffold and a motorized steering apparatus having an operative anchor that is fixed with respect to the scaffold unit moves the drive and steered wheel pivotally with respect to a vertically disposed axis of said scaffold for the directional control of said scaffold. The drive and steering motors are connected to a control panel that is movable to various elevated and/or remote locations. A power cord having a pivotally mounted and spring biased trailing arm is attached to the scaffold to prevent trapping of or damage to the power cord.

United States Patent 1 Hibma 1 SCAFFOLD DRIVE AND STEERING UNIT [75]Inventor: James Hibma, Westminster, C010.

[73] Assignee: Anne Marie Hibma, Westminster.

[22] Filed: Mar. 8, 1973 [21] Appl. No.: 339,260

[52] US. Cl. 180/2, 180/52, 180/65 F,

ISO/79.1, 182/16 [51] Int. Cl B60k 7/00 [58] Field of Search 180/11, 12,13, 52, 65 F,

180/65 R, 79, 79.1, 15, 16, 2; 182/13, 63, 16; 248/51, 54 R; 191/12 R[56] References Cited UNITED STATES PATENTS 1,644,661 10/1927 Aufenast248/51 2,635,703 4/1953 Goeller... 180/13 2,760,328 8/1956 Siebring191/12 R X 2,978,053 4/1961 Schmidt 180/65 R 3,099,332 7/1963 De Marco182/63 X 3,256,954 6/1966 Warthen.... 182/13 3,349,862 10/1967 Shirey180/52 X 3,438,456 4/1969 Hunter 180/104 51 Feb. 11, 1975 3,439,7644/1969 Kimball 180/12 3.503,466 3/1970 Rosander 180/11 X 3,731,7585/1973 Hibma 180/11 Primary E.\'aminerKenneth H. Betts AssistantExaminerTerrance L. Siemens Attorney, Agent, or Ft'rmC. B. Messenger[57] ABSTRACT Drive and steering attachments for application to and usewith scaffold units of the type used in connection with construction andmaintenance activities. A reversible drive motor associated with onescaffold sup-' port drive and steered wheel propels the scaffold and amotorized steering apparatus having an operative anchor that is fixedwith respect to the scaffold unit moves the drive and steered wheelpivotally with respect to a vertically disposed axis of said scaffoldfor the directional control of said scaffold. The drive and steeringmotors are connected to a control panel that is movable to variouselevated and/or remote loca' tions. A power cord having a pivotallymounted and spring biased trailing arm is attached to the scaffold toprevent trapping of or damage to the power cord.

14 Claims, 5 Drawing Figures f-"ATEMTED 3. 865.203

SHEET 1 0F 2 PATENTED 3.855.203

sum 2 OF 2 1 SCAF FOLD DRIVE'AND STEERING UNIT CROSS-REFERENCE TORELATED APPLICATION The present application is copending with respect toan earlier application of the same title filed Jan. 4, 1971, by thisinventor and bearing Ser. No. 103,555, now US. Pat. No. 3,73l,758. Thesubject matter and objectives of both applications are similar, but thedevelopments represent separate inventions.

BACKGROUND OF THE INVENTION In connection with construction ormaintenance operations, it is often advantageous for a workman to have ascaffold support so that he can work at high elevations with safety.Where ceilings or utilities are being installed or where lighting andheating systems are to be maintained, a rolling type scaffold is oftenused that may be conveniently moved to various work locations.Manipulation of the usual castor wheel supported scaffold generallyrequires an additional workman who can push and guide the scaffold andthe workmen supported thereby to successive work stations. In order toavoid this obvious misuse of labor, others have previously devisedscaffold propelling and steering systems that may be operated by aworkman at his elevated work station. In general, the previous systemshavev been quite expensive. It is believed that the overall expense andthe inconvenience of using and storing prior types of steering and driveapparatus have been detrimental to the widespread use of such systems.The present invention is intended to overcome shortcomings of theprevious systems.

SUMMARY OF THE INVENTION Briefly stated, the present invention providesattachments that may be applied to wheel supported scaffold units topropel the units and to steer the entire scaffold so that a singleworkman can move the scaffold and himself to successive work stations.Steering and drive functions are combined in a single attachment forapplication to one upright support of the scaffolding. The attachmentitself provides an anchor component for fixed positioning with respectto the scaffold upright support, and the major drive and steeringcomponents pivot with respect to such anchor and support. Motive drivemeans interconnect the provided anchor and the pivoting components tosteer the attachment, while drive power for moving the attachment andscaffold is applied to the wheel of such attachment. A power cord guidehaving a pivotally mounted spring biased trailing arm is attached to thescaffolding to prevent damage to the power cord.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showingan embodiment of the invention, a

FIG. 2 is a side elevation showing a power cord guide,

FIG. 3 is a top plan view showing features of the present embodiment,

FIG. 4 is a front elevation of the present embodiment, and

FIG. 5 is a side elevation of such embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of theinvention is shown in FIGS. 1-5. For this particular embodiment of theinvention the drive and steering functions and operations are combinedin a single attachment unit '70 that is applied to a single uprightstandard 77 of the scaffold unit 71. As in the mentioned previousapplication, this scaffold unit 71 is inclusive of end frames 72 and 73joined together by cross braces 74. The upright standards 76 for thescaffold unit 71 and the standard 77 are all of the same type so thatany particular scaffold unit is adapted for mating engagement in stackedarrangement with other scaffold units. The upright standard 77 to whichthe drive and steering unit is applied is identical with all theremaining upright standards 76 and the drive and steering unit 70 could,accordingly, be affixed to any of the upright standards. While a singlescaffold height is shown, the upper ends 78 of the upright standards areall adapted to receive the standards of mated scaffold units so that theentire scaffold system used on a maintenance or construction site couldbe two or more scaffold units high.

For convenience of usage the particular scaffold unit 71 illustrated isprovided with pneumatic wheel supports. The wheel supports 81 applied tothe upright standards 76 are all of the castor wheel type. These wheels,which may be of the type already used for the rolling support ofconstruction scaffolds, usually have a socket or plug (not shown)adapted for mating engagement with the upright standards of theparticular type of scaffold being used. The wheel supports 81conventionally provide a thrust bearing 82 that facilitates turningmovements of the wheels with respect to the associated standards 76.When used with 'a single at tachment unit 70,- the two rear wheels atthe opposite end of the scaffold 71 should be locked or held in fixedstraight-ahead position for best control of scaffold maneuveringoperations. Pneumatic tires are used where the scaffold unit is to beused over rough floors or uneve'n terrain. The drive and steering unitattachment 70 applied to the upright standard 77 is of overall heightcorresponding to the height of the castor support wheels 81.Accordingly, such a unit 70 may be applied to any of the uprightstandards 76 in substitution for the castor wheel units 81.

The single attachment unit 70 provides both drive and steeringcapability so that the entire scaffold 71 may be moved along randompaths from one work position to another. A remote control unit 49 isprovided which may be selectively attached to a cross bar 52 of scaffoldunit 71 at a position adjacent a work platform 53. Control unit 49 isinterconnected to the drive and steering unit 70 by a cable 84 which isof sufficient length so that the control unit 49 may be moved to higherelevations as the work platform is raised. Similarly the control unit 49can be hand carried by workmen at the floor level when the scaffold isto be moved from one work site to another. A power cord 88 is alsoutilized to deliver power to the drive and steering attachment andspecifically to a panel box 89 thereof. Since remote switchingcomponents may be positioned within the panel box 89, the cable 84 maybe of small wire and still carry the signals for regulating thesteering, driving and speed control operations of the drive and steeringunit 70.

As in the mentioned previous application, separate drive and steeringmotors 87 and 91 are used. Drive motor 87 serves to revolve the wheel 92while the steering motor 91 operates to move the wheel mount forks 96pivotally with respect to the axis of its associated upright standard77.

A beneficial arrangement of these components is more fully shown inFIGS. 3; 4 and 5. In these Figs. it will be noted that drive andsteering unit 70 is adapted for attachment to its upright standard 77when connector plug 97 is moved reciprocally into engagement in thehollow center 98 of the standard 77. Plug 97 is of size to be closelyengaged by the standard 77 so that a proportionate load of the scaffoldwill be efficiently transmitted to the supporting wheel 92. When theattachment assembly is in its fully engaged position as shown in FIG. 5,the end of standard 77 will be passed through a center opening 99 (FIG.3) in an anchor sprocket 101 to be engaged directly against a base plate102. The base plate 102 is similar in construction to plates provided ateach of the castor'wheels 81. The base plate structure 102 and the forks96 move rotatably one with respect to another, inasmuch as a thrustbearing 103 is interposed between such base plate and the supportingstructure for the forks 96. The anchor sprocket 101, which is slightlyraised above the base plate 102, is rigidly attached thereto by aplurality of spacers 104. A lock socket 106 is positioned above theanchor sprocket 101. A plurality of threaded lock pins 107 and 108 areengaged to the socket 106 for extension therewithin to engage theexterior walls of the standard 77. With this arrangement and with thestan dard 77 disposed about the plug 97 and extended through the anchorsprocket 101, the set screws 107 and 108 are turned inwardly to hold theanchor sprocket 101 and base .plate 102 in fixed position with respectto the standard 77.'With this arrangement the support wheel 92 is stillfree to move pivotally with respect to the standard 77 due to theinterposed thrust bearing 103. ln order to power turning movement of thesupport wheel 92 and itsassociated forks 96, a steering motor 91 isused. This steering motor 91 is mounted on an extension 116 ofa baseframe 114. The base frame 114 is itself rigidly attached to the wheelsupport forks 96 as' by welding or similar fastening means. The steeringmotor 91 includes a-gear reduction drive 111 so an increased torqueforce at slower speed will be delivered by the shaft 112 to a drivesprocket 113. A drive chain 117 interconnects the driving sprocket 113and anchor sprocket 101. Tension adjustments may be made for drive chain117, since the steering motor 91 is mounted on frame extension 116 by aplurality of adjustable mount bolts 118.

With the described arrangement, power from th steering motor 91 willcause rotation of drive sprocket 113, but since the anchor sprocket 101cannot move with respect to the upright standard 77, the drive sprocket113 will itself be caused to move orbitally about such anchor sprocket101. As drive sprocket 113 and steering motor 91 are thus caused to moveorbitally, the frame 114 will be moved in similarmanner thus rotatingthe support forks 96 of the wheel 92. This arrangement, accordingly,provides for directional steering of the scaffold support wheel 92.

For the present apparatus the powered rotation of the support wheel 92is attained in a manner similar to that described in the mentionedprevious patent. A drive motor 87 is disposed on the base frame 114 andis held in position thereon by a mount bolt 119. A drive sprocket 121 onthe shaft of jthe drive motor is connected by a chain 122 to a sprocket123 on ajack shaft 124. As in the previous patent, the jack shaft has anoutput sprocket 131 that is connected to a driven sprocket 133 forrotating the axle 134 of drive and support wheel 92. Adjustable mountingbolts 136 are provided to move the jack shaft mount reciprocally withrespect to the frame 114 to adjust the tension in the torque force canbe delivered to the wheel 92.

Except for the possibility of entanglement of'power or control cords orcables, the support wheel 92 could be freely rotated in excess of 360.Operation ofthe device at work sites has indicated, however, that eventhough full 360 rotation is desired or required, some turning limitationshould be imposed both to avoid destructive entanglement of the powerand control cables and to eliminate other job site abuses. In order tolimit steering rotation of the drive and steering wheel 92,microswitches are disposed within the panel box 89. Contact arms 1-37for such microswitches are positioned beneath the box .89 in a positionguarded by such box and also in position to be engaged by limit stops138 mounted on the steering drive chain 117. When the arms 137 areengaged by the stops 138, power to the steering motor will beinterrupted or reversed as desired. No turning movement in excess ofthat limited by the switch arms 137 and stops 138 can thereafter be madeby the remote operation of control unit 49. In addition to themicroswitches for such steer ing control the panel box 89 enclosesremote switching components so that it is not necessary to deliver fullmotor voltage to the control box 49. A reduced operational controlvoltage may be transmitted by the control cable 84 to the control unit49. A control circuit of reduced voltage is desirable where the workplatform may be of substantial height or adjacent to electrical circuitsof higher voltage or different phase than the power used for thesteering and driving'operations. In addition to enclosing any desiredoperational control circuits, the panel box 89 is of size and shape toprovide an operative guard for the steering chain 117. The ends of thepanel box 89 are, accordingly, positioned to cover the pinch areas ofthe drive sprocket 113 and of anchor sprocket 101. With this arrangementa separate chain guard is not required.

FIGS. 1 and 2 present an additional attachment for the scaffold unit 71which has been found to be highly beneficial. A power cord guide 141 isshown in these Figs. The guide 141 is adapted for attachment to a lowercross bar 152 of the scaffold unit 71. A C clamp 142 of such attachmentsurrounds the cross bar 152 and a lock screw 153 is used to securelyengage the attachment to the cross bar. A lower leg of the C frameprovides a pivot 154 and a trailing arm 156 is connected thereby to themounting clamp. The trailing arm has a terminal loop 157 through whichthe power cord 88 and any connector plugs 158 thereofmay be extended.After the cord is threaded through the loop 157, it is engaged and heldby a tie-down 159. The length of cord past the tie-down 159 can beregulated so that the segment 161 which delivers power to the attachmentwill at all times be held out of contact with the supporting floor or atleast in a non-interfering positionwith respect to all of the supportwheels of the scaffold. The other end of the cord 162 which passesthrough the loop 157, however, will oftentimes be disposed on thesupporting-floor in a position where it can be run over by any of thesupport or drive wheels of the scaffold. Powered back and forward andother steered movements of the scaffold can trap such end 162 of thepower cord 88 in a manner that would otherwise immobilize the scaffoldunit. Such scaffold unit disabling entrapment of the power cord isavoided by the attachment 141, since free swinging movement of thetrailing arm 156 is limited and controlled by a spring 163. This springand the tension adjusting link chain 164 permit pivoting movement of thetrailing arm 156. This pivoting movement to alternate positions assuggested in FIG. 1 is adequate to prevent the breakage of the powercord if the cord is trapped beneath any of the support wheels of thescaffold. After the cord is free from its entrapment, the trailing arm156 will be returned by the spring 163 to its at-rest position asindicated by the full line representation of FIG. 2. Movement of the arm156 from a trapped cord position to a free position is accomplishedrapidly in a manner that serves to move the trapped cord from itspreviously trapped position. The arrangement of pivot attachment pointsis adjusted so that the'maximum swinging mo tion for the arm 156corresponds to that shown in alternate position in FIG. 1. With thistype of limitation the arm 156 does not go past center, and the springwill accordingly always act to return it to a position as shown in thefull line representation of FIGS. 1 and 2.

As more fully described in the previous patent, the remote control unit49 shown in FIG. 1 will provide separate drive and starting controls.The toggle of the drive control may be moved to forward, neutral andreverse positions, while the toggle of the steering control is moved toleft and right positions to control the direction of rotation for thewheel 92. In the present embodiment the single attachment unit 70 may beused at any of the upright standards of a scaffold in substitution forthe support wheels thereof. Inasmuch as the attachment unit 70 providesits own anchor for steering operations, no modifications of the scaffoldare required.

The simplicity of installation and usage adds measurably to the on-siteuser benefits. With this type of scaffold unit a single workman mayinstall plumbing, electrical or heating utilities or suspended ceilingsor lighting systems. Similarly, the scaffold may be used for themaintenance of such systems as in the replacement of fluorescent lights,etc. A stock of parts may be carried to the upper supporting deck .53and thereafter a plurality of operations can be accomplished before aworkman would have to come down.

When not in use, the attachment unit 70 may be conveniently removed toprevent undesired use of the scaffold or theft of this major component.

I claim:

1. A drive and steering attachment for scaffolding type supports havingupright standards that in scaffolding usage may be mateably engaged oneabove another when multi-stages are to be used and wherein each of saidupright standards are further adapted to receive separate supportingwheel attachments when increased mobility is advantageous comprising aplurality of separable and separate wheel attachments for said supportwith a wheel attachment for each upright standard, wheels for each saidattachment, frame components for each attachment, wheel axles on saidframe components for the rotative support of said wheels, means forseparately and selectively engaging each of said wheel attachments withthe upright standards of said supports, means facilitating the rotativemovement of a first one of said frame components with respect to thevertically disposed axis of its associated upright standard to provide acastor type mounting therefor, an anchor element in non-movingrelationship with respect to said associated upright standard, motivedrive means interconnecting said anchor element and said first framecomponent to provide a steerable castor wheel attachment whereby saidfirst frame component and its associated wheel may be rotated toalternate radially directed positions with respect to the axis of itsassociated upright standard and said support, a mount adjacent said samefirst frame component and its wheel attachment, a motor drive unit onsaid mount and interconnected to the wheel of said first frame componentand attachment to power rotative movement of said wheel about its axle,and power control apparatus interconnected to said motive drive meansand said motor drive unit whereby an operator may conveniently steer anddrive said support unit.

2. The combination as set forth in claim 1 and further comprising atleast one additional castor wheel type attachment for the support ofsaid scaffolding.

3. The combination as set forth in claim 2 wherein said additionalcastor wheel attachment is rotatable to alternate radial positionsindependently of the move ment pattern for said steerable castor wheelattach ment and the motive drive means associated therewith.

4. The combination as set forth in claim 1 wherein said steerable castorwheel attachment is rotatable to full circle radial positions.

5. The combination set forth in claim 1 wherein said anchor element isdisposed at the upright standard for said steerable castor wheelattachment.

6. The combination set forth in claim 5 wherein said anchor element isconcentrically disposed with respect to the axis of the upright standardfor said steerable castor wheel attachment.

7. The combination set forth in claim 6 wherein the motive drive meansinterconnected to said anchor element moves orbitally about said anchorelement to steer said steerable castor wheel attachment.

8. The combination of claim 5 wherein said power control apparatus isinclusive of a panel box disposed on the said first frame component.

9. The combination set forth in claim 8 and additionally comprising aflexible type power transmission element interconnecting said motivedrive means and the anchor of said steerable castor wheel attachment.

10. The combination set forth in claim 9 and additionally comprising alimit stop component disposed for engagement by said power transmissionelement to limit the steering rotation of said steerable castor wheelattachment.

11. The combination set forth in claim 10 wherein said panel box ispositioned as a guard for the said limit stop and the pinch areas forsaid flexible type power transmission element.

12. The combination set forth in claim 1 and further comprising a powercord for trailed disposition from said drive and steering attachment, apower cord guide for attachment to said scaffoldsupport, a trailing armfor said guide, a pivot mount for said arm, a fastener for engaging saidcord to said trailing arm, and an elastic element for biasing saidtrailing arm to a first trailing position with movement away therefromresiliently deforming said elastic element whereby said cord is freedfrom entrapment by the scaffold support wheels as said trailing armreturns to said first position.

13. In wheel mounted mobile apparatus to be pow-' ment for biasing saidtrailing arm to a first trailing position directed away from -the wheelsof said apparatus with movement away from said first position due toforces applied by said power cord resiliently deforming said elasticelement whereby the cord is freed from entrapment by any wheels of saidapparatus by the return forces of said elastic element that tend toreturn the free end of said trailing arm toward said first position and,accordingly, away from any cord entrapping wheel.

14. The combination as set forth in claim 13 and further comprisingtension adjusting means for regulating the forces exerted-by saidelastic element.

1. A drive and steering attachment for scaffolding type supports havingupright standards that in scaffolding usage may be mateably engaged oneabove another when multi-stages are to be used and wherein each of saidupright standards are further adapted to receive separate supportingwheel attachments when increased mobility is advantageous comprising aplurality of separable and separate wheel attachments for said supportwith a wheel attachment for each upright standard, wheels for each saidattachment, frame components for each attachment, wheel axles on saidframe components for the rotative support of said wheels, means forseparately and selectively engaging each of said wheel attachments withthe upright standards of said supports, means facilitating the rotativemovement of a first one of said frame components with respect to thevertically disposed axis of its associated upright standard to provide acastor type mounting therefor, an anchor element in non-movingrelationship with respect to said associated upright standard, motivedrive means interconnecting said anchor element and said first framecomponent to provide a steerable castor wheel attachment whereby saidfirst frame component and its associated wheel may be rotated toalternate radially directed positions with respect to the axis of itsassociated upright standard and said support, a mount adjacent said samefirst frame component and its wheel attachment, a motor drive unit onsaid mount and interconnected to the wheel of said first frame componentand attachment to power rotative movement of said wheel about its axle,and power control apparatus interconnected to said motive drive meansand said motor drive unit whereby an operator may conveniently steer anddrive said support unit.
 2. The combination as set forth In claim 1 andfurther comprising at least one additional castor wheel type attachmentfor the support of said scaffolding.
 3. The combination as set forth inclaim 2 wherein said additional castor wheel attachment is rotatable toalternate radial positions independently of the movement pattern forsaid steerable castor wheel attachment and the motive drive meansassociated therewith.
 4. The combination as set forth in claim 1 whereinsaid steerable castor wheel attachment is rotatable to full circleradial positions.
 5. The combination set forth in claim 1 wherein saidanchor element is disposed at the upright standard for said steerablecastor wheel attachment.
 6. The combination set forth in claim 5 whereinsaid anchor element is concentrically disposed with respect to the axisof the upright standard for said steerable castor wheel attachment. 7.The combination set forth in claim 6 wherein the motive drive meansinterconnected to said anchor element moves orbitally about said anchorelement to steer said steerable castor wheel attachment.
 8. Thecombination of claim 5 wherein said power control apparatus is inclusiveof a panel box disposed on the said first frame component.
 9. Thecombination set forth in claim 8 and additionally comprising a flexibletype power transmission element interconnecting said motive drive meansand the anchor of said steerable castor wheel attachment.
 10. Thecombination set forth in claim 9 and additionally comprising a limitstop component disposed for engagement by said power transmissionelement to limit the steering rotation of said steerable castor wheelattachment.
 11. The combination set forth in claim 10 wherein said panelbox is positioned as a guard for the said limit stop and the pinch areasfor said flexible type power transmission element.
 12. The combinationset forth in claim 1 and further comprising a power cord for traileddisposition from said drive and steering attachment, a power cord guidefor attachment to said scaffold support, a trailing arm for said guide,a pivot mount for said arm, a fastener for engaging said cord to saidtrailing arm, and an elastic element for biasing said trailing arm to afirst trailing position with movement away therefrom resilientlydeforming said elastic element whereby said cord is freed fromentrapment by the scaffold support wheels as said trailing arm returnsto said first position.
 13. In wheel mounted mobile apparatus to bepowered from a fixed electrical power outlet and, accordingly, utilizinga power cord, a power cord guide attachment for use on said mobileapparatus, comprising mounting means for securing said guide attachmentto said mobile apparatus for movement therewith, a trailing arm for saidguide attachment, a pivot on said mounting means for rotatably holdingone end of said trailing arm, a fastener at a free end of said trailingarm for engaging said cord to the trailing arm, an elastic element forbiasing said trailing arm to a first trailing position directed awayfrom the wheels of said apparatus with movement away from said firstposition due to forces applied by said power cord resiliently deformingsaid elastic element whereby the cord is freed from entrapment by anywheels of said apparatus by the return forces of said elastic elementthat tend to return the free end of said trailing arm toward said firstposition and, accordingly, away from any cord entrapping wheel.
 14. Thecombination as set forth in claim 13 and further comprising tensionadjusting means for regulating the forces exerted by said elasticelement.